The Russian military has been raining bombs and artillery on the city for weeks but has been hesitant to risk storming it, for fear that street battles would cause the kind of heavy casualties that Russia suffered in Grozny in the 1994-96 war.

Now the Russians are threatening to unleash their biggest artillery and air bombardment on the city so far. The leaflets specified a safe corridor that would be open until Saturday for residents to use to flee Grozny.

"Persons who stay in the city will be considered terrorists and bandits and will be destroyed by artillery and aviation. There will be no further negotiations. Everyone who does not leave the city will be destroyed," the leaflets said.